The invention concerns an electrical model railway set having a stationary current source connected to tracks or to an overhead line, a stationary central station for generating control signals capable of being coupled to the tracks or to the overhead line, furthermore a plurality of model vehicles movable on the tracks, drawing electrical current from the tracks or from the overhead line, and drivable by electrical torque motors, as well as control signal receivers located on the respective model vehicles for extracting the control signals intended for a model vehicle and for supplying an adjustable electrical drive energy for the respective electrical torque motor for controlling the rotary speed thereof.
What is generally known are electrical model railway sets of this type, wherein DC motors or universal motors serve for driving the model vehicles, which receive the electrical drive energy through the tracks or through the overhead line and which are equipped with slip rings or commutators in order to feed electrical currents to the windings of the rotor.
The rotary speed of the motors for driving the model vehicles is obtained by controlling the terminal voltage, with control signals being encoded, e.g. digitally, in a central station, coupled to the tracks or to the overhead line, decoded in the single model vehicles by means of a decoder, and then controlling the terminal voltage of the electrical drive motors and thus the rotary speed thereof.
In recent years, digital controls for simultaneously operating a plurality of model vehicles on an electrical model railway set have become customary, with these digital controls serving not only for controlling the velocity of a plurality of model vehicles but also for actuating further consumers connected to the track system, such as points, signals and the like.
Model railway sets of the above considered type are discussed for example in DE-PS-42 25 277 and provide, for controlling portions of the set, the transmission of control signals via the tracks, with these control signals having to be regarded as data which present an address portion for allocation to the desired powered vehicles, and a data portion for determining direction of movement, moving velocity and possible special functions such as lighting.
Whereas the reception of electrical energy by the movable model vehicles from the tracks and from the overhead line may be devised to be substantially free of interference by suitable contacting constructions and associated auxiliary means, the use of DC motors or of universal motors having an analogous construction has the drawback of sparking occurring at the slip rings or commutators of these motors, with this sparking causing interferences in a very broad frequency band and thus being in contradiction with the requirements of electromagnetic compatibility (EMC).
Shielding the interferences induced by slip ring or commutator sparking on model vehicles causes considerable problems as these interferences also invade the entire line system which then acts as an antenna for interference signals.
DE-PS 866 814 describes a small-size rotary field motor or induction motor comprising in one of its embodiments a stator which can be supplied with polyphase current for generation of a rotary magnetic field, whereas the rotor does not comprise a slip ring. This known small-size motor is also intended for use in driving toy railways. Means for speed control of the small-size motor are not disclosed in the named patent specification.